1. Field of the Invention
The present invention relates to a method of making an electrochemical capacitor electrode, an electrochemical capacitor electrode, an electrochemical capacitor, and a method of making the same.
2. Related Background Art
Electrochemical capacitors such as electric double layer capacitor are easy to reduce their size and weight, so that demands therefor have rapidly been increasing in these years as backup power supplies for power supplies of portable devices (small-size electronic devices) and auxiliary power supplies for electric cars and hybrid cars, for example. For improving their performances, various studies have currently been in progress.
For example, when a large capacity is needed as in the case of power supplies for electric cars, high-output electrochemical capacitors having a low internal resistance with a high energy density per unit mass and a high energy density per unit volume have been in demand for development. Small-size capacitors for memory backup and the like have been required to reduce their internal resistance as well.
Known as such electrochemical capacitor electrodes and electrochemical capacitors are those manufactured by the methods disclosed in Japanese Patent Application Laid-Open Nos. HEI 11-283887 and 9-36005. Japanese Patent Application Laid-Open No. HEI 11-283887 discloses the realization of an electric double layer capacitor having a high capacity density and a low internal resistance by screw-extruding a mixture made of a carbonaceous material, polytetrafluoroethylene, and a processing aid, and extending thus extruded product with pressure rolls so as to form a sheet. On the other hand, Japanese Patent Application Laid-Open No. HEI 9-36005 discloses the realization of an electric double layer capacitor having a higher density electrode by mixing activated carbon powder and PTFE so as to yield a paste, applying the paste to a collector, drying the paste by heating it to the melting point of PTFE or higher, and press-molding the product so that the electrode becomes a thin film.